OBJECTIVE To investigate factors associated with postvitrectomy endophthalmitis. METHODS Cases with postvitrectomy endophthalmitis in our hospital between 2003 and 2007 were collected and retrospectively reviewed. RESULTS All 14011 cases (eyes) underwent pars plana vitrectomy and postoperative endophthalmitis happened to seven cases (eyes). The incidence of infection was 0.047%. Confirmed microbiology was demonstrated in 4 of 7 cases (57.0%),in which Gram-positive cocci were found 75.0%. 71.4% Of cases with postvitrectomy endophthalmitis were older than 60. The infection was controlled in 6 cases after antibiotic treatment. One case with diabetes and culture confirmation of Gram-negative bacilli deteriorated even after the second vitrectomy,and evisceration was finally performed. CONCLUSIONS The predominant organism is Gram-positive cocci in postvitrectomy endophthalmitis. The risk factors include increasing age,presence of systemic diseases and immunodeficiency. Timely and effective antibiotic therapy is important to restore visual acuity for postvitrectomy endophthalmitis.